1. Field of the Invention
The present invention relates to a composition for removing copper (Cu)-compatible resist, and more particularly, to a composition for removing copper-compatible resist without corrosion of copper.
2. Discussion of the Related Art
In general, a low resistance copper line is commonly used as an array line of an array substrate for a liquid crystal display (LCD) device, or in a circuit line of a semiconductor device to prevent resistance-capacitance (RC) delay. The copper line is commonly formed using a photolithographic process incorporating fine pattern technology. The photolithographic process is commonly used for fabricating semiconductor devices such as large scale integrated (LSI) circuits, very large scale integrated (VLSI) circuits, and display devices including LCD and plasma panel display (PDP) devices.
FIG. 1 is a perspective view of a liquid crystal display device using a copper line according to the related art. In FIG. 1, a liquid crystal display (LCD) device 11 includes an upper substrate 5, a lower substrate 10, and a liquid crystal material layer 9 interposed between the upper and lower substrates 5 and 10. The upper substrate 5 includes a color filter layer 7, a black matrix 6, and a common electrode 18. The lower substrate 10 includes a pixel electrodes 17 formed at pixel regions “P,” and thin film transistors (TFTs) “T” that function as switching devices. The TFTs “T” are disposed in a matrix configuration and gate and data lines 14 and 22 are connected to each of the TFTs “T.” The pixel regions “P” are each defined by a crossing of the gate and data lines 14 and 22, and a transparent pixel electrode 17 is formed at each of the pixel regions “P.” The transparent pixel electrode 17 and the common electrode 18 are made of a transparent conductive metal such as indium-tin-oxide (ITO) and indium-zinc-oxide (IZO), and the LCD device is driven by utilizing an electro-optical effect of the liquid crystal material layer 9. Accordingly, the gate line 14 should be made of a low resistance material such as copper (Cu), and should be formed using a photolithographic process incorporating fine pattern technology.
FIGS. 2A to 2E are cross-sectional views of a photolithographic process for forming a metal line according to the related art. In FIG. 2A, a metal layer 32 is formed on a substrate 30 by deposition of a metallic material. Next, a photoresist (PR) 34 of positive or negative type is formed on the metal layer 32. In FIGS. 2A to 2E, a positive type PR will be illustrated. Even though the PR 34 may be formed on an entire or a predetermined region of the substrate 30, the PR 34 is generally formed on the entire region of the substrate 30.
In FIG. 2B, a photo mask 36 is disposed over the PR 34 of the substrate 30. Next, an exposure process is performed, wherein a light “L” such as an ultra violet (UV) ray and an X ray is irradiated onto the photo mask 36. The photo mask 36 includes a transmitting portion “T” and a shielding portion “S,” wherein the light that passes through the transmitting portion “T” transforms the PR 34. Accordingly, the PR 34 includes a first portion “A” where a material property of the PR 34 is maintained and a second portion “B” where a material property of the PR 34 is transformed. Since the PR 34 is potentially patterned according to the photo mask 36, this pattern of the PR 34 is referred to as a latent image.
In FIG. 2C, the PR 34 (of FIG. 2B) having the latent image is developed to form a resist pattern 35 that corresponds to the photo mask 36 (of FIG. 2B). Specifically, the first portion “A” (of FIG. 2B) where the light “L” (of FIG. 2B) is not irradiated remains to cover the metal layer 32 and the second portion (of FIG. 2B) where the light “L” (of FIG. 2B) is irradiated is eliminated to expose the metal layer 32.
In FIG. 2D, the metal layer 32 (of FIG. 2C) is etched using the resist pattern 35 as an etching mask, whereby a metal line of a specific shape is formed on the substrate 30.
In FIG. 2E, the resist pattern 35 (of FIG. 2D) is eliminated and the metal line 38 of the specific shape is exposed.
However, the metal line formed of copper may be easily corroded by conventional solvents that are used to remove the resist pattern during the photolithographic process. Accordingly, solvent compositions that include a corrosion inhibitor for preventing corrosion of copper may be used, as demonstrated by U.S. Pat. Nos. 5,417,877 and 5,556,482, which are hereby incorporated by reference. The corrosion inhibitors include mono-ethanol-amine (MEA) as a preferred amine. In addition, a specific amount of corrosion inhibitor is required so that a removing property of the inhibitor is not degraded.